Annihilation, with gradients

Figure 20. Artificial muscle under work. In reduction (A) electrons are injected into the polymer chains. Positive charges are annihilated. Counter-ions and water molecules are expelled. The polymer shrinks and compaction stress gradients appear at each point of the interface of the two polymers. The free end of the bilayer describes an angular movement toward the left side. (B) Opposite processes and movements occur under oxidation. (Reprinted from T. F. Otero and J. Rodriguez, in Intrinsically Conducting Polymers An Emerging Technology, M. Aldissi, ed., pp. 179-190, Figs. 1,2. Copyright 1993. Reprinted with kind permission of Kluwer Academic Publishers.)...

Two final remarks should be made concerning the validity of this approximate calculation. (1) If point defects are created or annihilated at a dislocation line, this line moves through the lattice (climb). It is assumed that the distance of this nonconservative movement is small compared with (2) Because of the cylindrical symmetry of the problem, the main diffusion resistance (i. e. the highest concentration gradient of the defects) is found in the immediate neighbourhood of the dislocation line. Therefore the specific spatial distribution of the dislocation lines is not very important for the given estimate of the relaxation time t. 

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